MCB136 Spring 2008 Study Guide for Prof. Machen’s portion of Exam 2 Skeletal vs cardiac vs. smooth muscle: Anatomy, including actin and myosin, sarcomeres for all types of muscle, including similarities and differences; tropomyosin and troponin for skeletal and cardiac; myosin light chain kinase and myosin light chain, and myosin light chain phosphatase for smooth muscle; gap junctions for smooth and cardiac muscle, not for skeletal. See Table 12-3 p. 169 Reader for summary. Action potential mechanisms, incl. ion channels responsible for different phases for cardiac and skeletal. Refractory period comparison of skeletal vs. cardiac muscle, including implication for sustained contractions in skeletal vs. cardiac. Different ion channels and ion transporters present in plasma and SR membranes, incl. Na/Ca exchanger in cardiac muscle plasma membrane, RyR in cardiac and skeletal muscle and IP3 receptor in smooth muscle SR membranes. SERCA in SR of all, and phospholamban in cardiac muscle. Roles of autonomic nerves in control of cardiac muscle action potential and Ca entry into cytosol of cardiac muscle. Smooth muscle responses to hormones like epinephrine and sympathetic nerves release of norepinephrine. Sympathetic stimulation generally leads to contraction of arterioles (vasoconstriction) leading to most tissues but dilation of arterioles leading to most skeletal muscle, heart and liver. Roles of ATP in contraction and relaxation of all three types of muscle. Muscle spindles: intra- and extra-fusal fibers, sensory nerves, alpha and gamma motor neurons, muscle tone, stretch (knee-jerk reflex), monosynaptic Heart structure and function: aorta and vena cava, atria and ventricles, flow-regulating valves composed of connective tissue, papillary muscles, chordae tendinae, SA and AV nodes, bundle of His, bundle branches, Purkinje fibers; SA node autorhythmicity, mechanisms of generation of action potentials, and effects of sympathetic and parasympathetic nerves (transmitters Ach and norepinephrine). Arteries, arterioles, veins, venules and capillaries: know anatomies (amount of connective tissue, fibrous and elastic, smooth muscle and endothelial cells), relative blood velocities through each, blood pressures, amount of blood in each compartment, areas available for diffusion, relative resistance to blood flow for aggregate as well as individual vessels — individual capillary has high resistance, but many capillaries in parallel have low resistance. Major functions of each type of vessel. Which has the highest and lowest compliance ("stretchiness", defined as change in volume for given change in internal pressure, C = ∆V/∆P) among arteries (lowest), arterioles and veins (highest)? What anatomical structures account for the differences? Capillaries: relative oxygen and carbon dioxide concentrations in blood and tissues, roles of arterioles and precapillary sphincters in controlling blood flow, and mechanisms of regulation, metabolism control (build up of CO2, lactic acid, adenosine and K, depletion of O2) and sympathetic nerves (act on arterioles but not on precapillary sphincters). What controls delivery of oxygen and glucose from blood to tissues and of carbon dioxide and lactic acid and other wastes from tissues to capillaries? (diffusion equation). Control of water flux between capillaries and tissure spaces: roles of hydrostatic and osmotic pressures; effects of different physiological conditions, incl. decreased arterial blood pressure during hemorrhage, arteriolar dilation (vasodilation) vs arteriolar constriction (vasoconstriction), increased venous pressure, blocking lymph vessel flow. How do venous vessels control fluid flow back to the cardiovascular system? What is solute and water composition of lymph vs. plasma vs. tissue fluid? Some numbers to remember: Arterial pressure =120/80 mm Hg avg approx = 100 mm Hg; pulmonary pressures about 1/5 as large (compare resistance of systemic and pulmonary circulations). Cardiac output = 5 l/min; blood volume = 5 l; most blood volume is in the veins at any one time (about 60%); EDV = 135 ml, ESV = 65 ml; blood flow through aorta = blood flow through vena cava = 5 l/min Blood flow and pressure: Laminar (quiet) vs. turbulent (noisy — murmurs) flow. Poiseulle’s law, ∆P = flow x resistance, where resistance is inversely proportional to r4. Effects of vasoconstriction and
vasodilation of one specific arteriole on arterial blood pressure and on blood pressure at entrance of capillary at the “end” of the arteriole — Fig. 15-14 and #29 on p. 532. Law of Laplace and role of vessel diameter on tension required to maintain pressure in the vessel: T required is proportional to P and inversely proportional to radius of vessel, T P/r. Thus, capillaries with very thin walls (1000 times thinner than aorta) are able to withstand pressures that are only four times lower than in the aorta. Wiggers diagram Identify systolic and diastolic pressures in left ventricle and in aorta, phases of systole and diastole (isovolumetric contraction, ejection, isovolumetric relaxation, filling),.EDV and ESV and SV; be able to show at what points on the graph atrio-ventricular and aortic valves shut, yielding heart sounds. Starling’s Law of the Heart and control of venous return by respiratory pump (deep breathing) and muscle pump (rhythmic contractions and relaxations, not sustained isometric contractions). Effects of sympathetic stimulation on venous return. Control of blood pressure: baroreceptors, cardiovascular center in medulla oblongata, autonomic nerves, effects on heart, arterioles, veins. Example: low blood pressure during hemorrhage Material in reader that was not covered and which you will not be tested on: E + P + gravitational factor (p. 208) Reynold's number and turbulent flow, p. 209, figs on p. 219 Total fluid energy p. 210, top fig. p. 220 Areas, velocities and volumes on p. 211 Details of Law of Laplace p. 213 and fig. p. 225 Compliance p. 235 Changes in kidney p. 237 Blood flow and pressure reg. pp. 233-236 and 238-244 — covered in class using different figures. Exercise: pp. 254-262 Go over review questions in Reader: pp. 189-193, 203-204 (omit p. 203, #8, 9), 247-253 (omit p. 247, #5, p. 248 #9, 10, 12, 16, 18 and p. 250 #27, 28, 30)